It is difficult, if not impossible, to form ionomer foams with conventional extrusion apparatus operating at design throughput. The difficulty is that when a temperature suitable for extrusion foaming is reached, the pressure in the extruder is high enough to damaging the apparatus. As a result, it is necessary to decrease the extrusion volume.
The alternative is to build heavier apparatus with safety design features, and this undesirably increases production costs.
Foams produced solely from ionomer resins are generally recognized as inferior in both rigidity and thermal resistance. Foams produced solely from homo-polyolefins generally have inferior adhesion properties. Neither of the foams are satisfactory for, for example, a covering on pipes for an air conditioner which requires in balance all of the properties in addition to heat insulation property.